Identification Method Investigation Of Supersonic Combustor Wall Heat Flux

Superonic combustor, as the main power source of the scramjet engine, is one of the key components impacting on the scramjet performance. Predicting the thermal environment of the engine is important on the design of the engine, the cooling system and the predition of the engine performance. Heat flux is an important indicator of the thermal environment. However, it is extremely difficult to measure the heat flux due to the extreme inner thermal environment of the combustor. This paper presents a calculation method of the heat flux based on the measured outer wall temperature in order to indentify the heat flux accurately.Firstly, one-dimensional and two-dimensional calculation models of the heat flux are established for the supersonic combustor. The wall temperature of combustion chamber is closely related to the work process of the engine. The wall thermal conductivity is unsteady in the short woring process of the combustor. According to the unsteady heat conduction characteristic, the heat conduction control equations of the wall are obtained, using the second boundary condition. The relation between the combustor heat flux and the wall temperature is acquired through formula derivation. The simulation model is set up based on the control equations, which can accurately calculate the unsteady heat conduction process of the wall in a given heat flux boundary condition. The result tells that this system identificaiton method is of high accuracy in calculating the combustor heat flux using the measured outer wall temperature.Secondly, the simulation model of the supersonic combustor heat flux is set up. The scramjet combustor outer wall temperatures under different conditions are measured, which are used to identify the combustor heat flux through the one- and two-dimensional heat flow calculation models. The results shows that the main combustion region of the supersonic combustion chamber is on the latter two sections of the supersonic combustion chamber and mainly in the middle area.Finally, the test bed of thermal protection system is established using the high-enthalpy air flow generator as the heating source to simulate the thermal environment of the scramjet engine. The heat flux system identification method is used to calculate the heating capacity of the high-enthalpy air flow generator based on the measured outer wall temperatures. It shows that the heat flux level is the same as that of the scramjet combustor. Therefore, the high-enthalpy air flow generator could be used to simulate the thermal environment of the combustion chamber. It could simplify the experimental process for the thermal protetion system design and save the experiments cost.